U.S. patent application number 15/508498 was filed with the patent office on 2017-10-19 for textile fabric for preventing the penetration and the spreading of water in cables.
The applicant listed for this patent is Carl Freudenberg KG. Invention is credited to Gerald Jarre, Dominic Kramer, Ulrich Schneider, Matthias Schuster, Iain Smith, Marco Sutter, Nermina Zaplatilek.
Application Number | 20170298568 15/508498 |
Document ID | / |
Family ID | 54072814 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170298568 |
Kind Code |
A1 |
Kramer; Dominic ; et
al. |
October 19, 2017 |
TEXTILE FABRIC FOR PREVENTING THE PENETRATION AND THE SPREADING OF
WATER IN CABLES
Abstract
A textile fabric for preventing the penetration and water
spreading in cables, having at least one layer, which is at least
partially covered by an absorbent material and has pores, which
pores can be at least partially closed under the effect of liquid
due to absorbent material swelling, the absorbent material being
bonded to the textile layer, at least in some areas, has a DIN ISO
9073-3 tensile strength in machine direction of >50 N/5 cm, and
obtainable by a method involving: treating a layer containing pores
with a mixture containing a polymerizable monomer or oligomer and a
cross-linking agent and, as absorbent material precursor, a wetting
agent and initiator, and polymerization of the monomer or oligomer
under formation of a bonded connection between the absorbent
material and the layer. The textile fabric can have a DIN EN ISO
9237 air permeability in dry state of greater than 200
dm.sup.3/(m.sup.2s).
Inventors: |
Kramer; Dominic; (Frankfurt,
DE) ; Schneider; Ulrich; (Darmstadt, DE) ;
Jarre; Gerald; (Weinheim, DE) ; Schuster;
Matthias; (Weinheim, DE) ; Zaplatilek; Nermina;
(Birkenau, DE) ; Sutter; Marco; (Weinheim, DE)
; Smith; Iain; (Watchfield Swindon, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carl Freudenberg KG |
Weinheim |
|
DE |
|
|
Family ID: |
54072814 |
Appl. No.: |
15/508498 |
Filed: |
September 1, 2015 |
PCT Filed: |
September 1, 2015 |
PCT NO: |
PCT/EP2015/069940 |
371 Date: |
March 3, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D06M 10/001 20130101;
D06M 10/10 20130101; D06M 15/263 20130101; G02B 6/44 20130101; G02B
6/4494 20130101; H01B 7/288 20130101; D06M 14/26 20130101; B05D
7/20 20130101 |
International
Class: |
D06M 15/263 20060101
D06M015/263; D06M 10/00 20060101 D06M010/00; D06M 14/26 20060101
D06M014/26; H01B 7/288 20060101 H01B007/288 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 4, 2014 |
DE |
102014 012 888.1 |
Claims
1. A textile fabric for preventing penetration and water spreading
in cables, the fabric comprising: a layer, at least partially
covered by an absorbent material, the layer comprising pores
configured to be at least partially closed under an effect of
liquid due to a swelling of the absorbent material, wherein the
absorbent material is bonded to the textile layer at least in some
areas, wherein the absorbent material has a tensile strength in the
machine direction of more than 50 N/5 cm, measured according to DIN
ISO 9073-3, and wherein the textile fabric has an air permeability
according to DIN EN ISO 9237 in a dry state of more than 200
dm.sup.3/(m.sup.2s).
2. The fabric of claim 1, wherein the textile layer comprises a
fiber comprising a polyolefin, polyester, polyamide, polyvinyl
chloride, polyacrylonitrile, polyimide, polytetrafluoroethylene,
aramid, wool, cotton, silk, hemp, bamboo, kenaf, sisal, cellulose,
soya, flax, glass, basalt, carbon, viscose, or a mixture of two or
more of any of these.
3. The fabric of claim 1, having a thickness according to DIN EN
9073-2 of 0.1 to 3 mm.
4. A method for producing the fabric of claim 1, the method
comprising: a) treating the layer with a mixture comprising a
polymerizable monomer or oligomer and a cross-linking agent, as
precursor for an absorbent material, a wetting agent, and an
initiator; and b) polymerizing the monomer or oligomer so as to
form a bonded connection between the absorbent material and the
layer.
5. The method of claim 4, wherein the wetting agent comprises a
compound of formula RO(CH.sub.2CH.sub.2O).sub.xH, wherein R is a
linear or branched alkyl residue, and wherein x=4, 5, 6.3, 6.5, 7,
8, 9, 10, or 11.
6. The method of claim 4, wherein a proportion of the wetting agent
based on a total quantity of the mixture is in a range from 0.1 to
5 wt. %.
7. The method of claim 4, further comprising: setting a surface
tension according to DIN 55660, using the wetting agent, of the
mixture to a range of from 10 to 72 dyn.
8. The method of claim 4, comprising: achieving a degree of
cross-linking in a range of from 4.7.times.10.sup.-5 to
1.9.times.10.sup.-1.
9. The method of claim 4, wherein the polymerizable monomer or
oligomer comprises an acrylic acid, methacrylic acid, amides,
vinylsulfonic acid, or a mixture of two or more of any of
these.
10. The method of claim 4, wherein the polymerizing b) comprises
forming a super-absorber.
11. A method of preventing penetration and spreading of water in a
cable, the method comprising: including the fabric of claim 1 into
the cable.
12. A sealing element of one or more cavities in a data, signal,
glass fiber, or telecommunications cable, or cable suitable for
power transmission, the element comprising the fabric of claim
1.
13. A sealing along one or more open channels in a single cable,
cable bundle, and/or between cable layers, and/or covering of
single cable layers.
14. An arrangement, comprising: a sealing element comprising the
fabric of claim 1, configured to seal a cavity in and/or above a
conductor, over and/or under a shielding, in and/or over and/or
under a sheathing of a power transmission cable.
15. A method of protecting a cable, the method comprising: cutting
the fabric of claim 1 into a tape and/or spinning the fabric into a
yarn as sealing along an open channels in a conductor area; and
providing the fabric above and/or below a shielding element of the
cable and/or in the conductor area as covering of a conductor core
and/or one or more conductor segments of a segmented conductor
and/or within the conductor core or the conductor segments.
16. The fabric of claim 1, produced by a process comprising: a)
treating the layer with a mixture comprising a polymerizable
monomer or oligomer and a cross-linking agent, as precursor for the
absorbent material, a wetting agent, and an initiator; and b)
polymerizing of the monomer or oligomer thereby forming a bonded
connection between the absorbent material and the layer.
17. The fabric of claim 2, wherein the fiber comprises
polyphenylene sulfide, polyethylene terephthalate, polybutylene
terephthalate, polyamide 6.6, and/or polyamide 6.0.
18. The method of claim 5, wherein x is 6.5, 7, 8, 9, or 10.
19. The method of claim 5, wherein x is 6.5, 7, 8, or 9.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. national stage application under
35 U.S.C. .sctn.371 of International Application No.
PCT/EP2015/069940, filed on Sep. 1, 2015, and claims benefit to
German Patent Application No. DE 10 2014 012 888.1, filed on Sep.
4, 2014. The International Application was published in German on
Mar. 10, 2016, as WO 2016/034578 A1 under PCT Article 21(2).
FIELD
[0002] The invention relates to a water-blocking textile fabric.
The invention further relates to a method for producing the textile
fabric and to the use thereof for preventing the penetration and
the spreading of water in cables.
BACKGROUND
[0003] Cable systems, for example underground cable systems,
including power (energy) cables or data communications and
telecommunications cables and in particular cable systems passing
through water, are very sensitive to damage and destruction wherein
water penetrates into the cable core and spreads along the cable.
Considerable damage and complete failures of the functionality of
the cable systems can be caused thereby.
[0004] Many cable products are endowed with one or more
water-blocking protective layers for protection against the
penetration and the spreading of water. For example, watertight
sheaths, water-blocking layers, which are inserted between a
central core and a core or sheath, water-blocking yarns,
water-blocking tapes and combinations thereof are used for this.
Such water-blocking protective devices act against penetration of
water in the direction of areas of the central core, which for
example contains optical fibers, and spreading of the water along
the cable axes which would lead to damage of further sections of
the cable.
[0005] Layered water-blocking tapes have the disadvantage that
during cable production the active water-blocking compounds can
sometimes be partially lost for example by mechanical abrasion. In
order to prevent this, water-blocking tapes are often sealed or
bonded with adhesives and adhesives. However, such adhesives and
adhesives are disadvantageous, since they inhibit the swelling
action and swelling rate of the water-blocking compounds and thus
impair the water-blocking properties of the tapes. In addition, the
use of binders increases the weight of the coated materials.
Water-soluble binders and adhesives are normally used. As a result
of this, the binder dissolves on contact with water and the
water-blocking compound begins to swell. As a result, the
water-blocking agent loses its attachment to the substrate and can
thus be flushed out in the event of damage to the cable and under
water pressure can migrate along cavities in cables.
[0006] DE 4134370C1 describes a swellable cable band layer,
consisting of a nonwoven which is coated with super-absorbers in
powder form by means of an adhesive. In this publication, the
problem of powder attachment by means of a binder is discussed with
regard to the free swellability or degree of swelling for cable
use. A compromise between powder attachment and swellability is
proposed.
[0007] Consequently it would be desirable to obtain a textile
fabric with which the spreading of water in cables can be
effectively prevented. The textile fabric should as far as possible
do without adhesives and/or adhesives, in order to maximize the
swelling action and swelling rate. Further, it would be desirable
for the textile fabric to have a low weight and sufficient
flexibility for use in a wide variety of cable configurations.
[0008] Also known is the use of fibers which consist of
super-absorbers (SAP fibers). However, a disadvantage with these
fibers is that in the swelled state they display low gel strength.
The SAP fibers are also not firmly bound in or around the matrix
fibers. Under hydrostatic pressure, the gel migrates very rapidly
along cavities in the cable.
[0009] From DE 000069609828 T2, a water-blocking composite material
is known, comprising a substrate which is coated with a mixture of
an irradiation-polymerized compound and a compound swellable in
water. As substrates, fibers (glass fibers, yarns, optical fibers),
wires or rods (e.g. components subject to cable drawing) or tubes
(e.g. polymer cable sheathings or buffer sheaths) or other articles
are used. These are endowed with the swellable compound and a
coating of variable thickness is thus formed. With the formation of
coatings as described in this publication, it is disadvantageous
that such composite materials are only to a limited extent suitable
for preventing the spreading of water in the longitudinal direction
along the cable. In particular, the composite materials have a
rather low swelling--and thus blocking--rate. In addition, no firm
bonding to the substrate can be achieved through the application of
the swellable compound as a coating. This leads to detachment of
the swellable compound during production and/or in use, for example
on contact with water.
SUMMARY
[0010] An aspect of the invention provides a textile fabric for
preventing penetration and water spreading in cables, the fabric
comprising: a layer, at least partially covered by an absorbent
material, the layer comprising pores configured to be at least
partially closed under an effect of liquid due to a swelling of the
absorbent material, wherein the absorbent material is bonded to the
textile layer at least in some areas, wherein the absorbent
material has a tensile strength in the machine direction of more
than 50 N/5 cm, measured according to DIN ISO 9073-3, and wherein
the textile fabric has an air permeability according to DIN EN ISO
9237 in a dry state of more than 200 dm.sup.3/(m.sup.2s).
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will be described in even greater
detail below based on the exemplary figures. The invention is not
limited to the exemplary embodiments. All features described and/or
illustrated herein can be used alone or combined in different
combinations in embodiments of the invention. The features and
advantages of various embodiments of the present invention will
become apparent by reading the following detailed description with
reference to the attached drawings which illustrate the
following:
[0012] FIG. 1 is a schematic view of a textile fabric with complete
coating;
[0013] FIG. 2 is a detailed view of the textile fabric shown in
FIG. 1 in the dry state;
[0014] FIG. 3 is a detailed view of the textile fabric shown in
FIG. 1 under the action of liquid;
[0015] FIG. 4 is a schematic view of a textile fabric with partial
coating;
[0016] FIG. 5 is a detailed view of the textile fabric shown in
FIG. 4 in the dry state;
[0017] FIG. 6 is a detailed view of the textile fabric shown in
FIG. 4 under the action of liquid; and
[0018] FIG. 7 is a schematic representation of the layer-wise
structure of a cable for power transmission.
DETAILED DESCRIPTION
[0019] An aspect of the invention is therefore to provide a
water-blocking textile fabric which no longer displays the
aforesaid disadvantages of the prior art. In particular, a textile
fabric is to be provided wherein the use of super-absorbers in
powder form and adhesives can be dispensed with and which,
simultaneously with inexpensive production, can when used in and/or
on cables effectively act against the spreading of water in the
longitudinal direction along the cable in case of damage.
[0020] Accordingly, the textile fabric mentioned at the outset is
characterized in that it has an air permeability, measured
according to DIN EN ISO 9237 at 100 Pa air pressure of more than
200 dm.sup.3/(m.sup.2s), preferably in the range from 300 to 5000
dm.sup.3/(m.sup.2s), more preferably from 500 to 3000
dm.sup.3/(m.sup.2s), and most preferably in the range from 800 to
2500 dm.sup.3/(m.sup.2s). The measurements of air permeability were
performed before contacting with liquid with samples of thickness
0.1 to 3 mm, preferably 0.3 mm, an air-permeated sample area of 20
cm.sup.2, at an air pressure difference of 100 Pa.
[0021] It was found that the textile fabric according to the
invention, in spite of its high air permeability, makes it possible
effectively to prevent the penetration and the spreading of water
in the direction of the longitudinal axis of cables (high
longitudinal impermeability).
[0022] For a person skilled in the art it was surprising that
products with high air permeability display a good sealing action,
since it was obvious to use for this purpose products which already
have high impermeability in the dry state. The air permeability is
a measure of the open porosity of the textile fabric. According to
the invention, however, it was found that it is precisely the high
air permeability and open porosity of the fabric which enable rapid
and comparatively unhindered swelling of the absorbent and thus
efficient sealing against the entry of water and sealing against
the further transport of water along the longitudinal axis of the
cable. Also surprising was the fact that the high air permeability
and open porosity causes particularly good anchoring of the dry,
but also of the swelled absorbent medium in the textile fabric.
This results in especially effective longitudinal sealing, since a
migration of the swelled absorbent medium under external water
pressure is markedly restricted. As is known to a person skilled in
the art, the high air permeability of the textile fabric can be
adjusted by adjustment of various parameters, for example the
choice of a suitable open-pored substrate, of process parameters
during the application of the material, for example viscosity, the
quantity of absorbent and implementation of a suitable
after-treatment of the material (washing and drying, mechanical
after-treatment).
[0023] Without committing to one mechanism according to the
invention, it is surmised that according to the invention an
interpenetrating network of fibers and cross-linked absorbent is
formed, which at least partially can be firmly bonded onto the
textile layer and thus can be firmly anchored even without the use
of additional adhesives. Additional adhesive is understood to mean
an adhesive which has been added to the polymerizable mixture
during the production of the textile fabric, for example polymeric
binders such as polyacrylates, polyvinyl alcohol, polyvinyl
acetate, polyurethanes, styrene-butadiene rubber, nitrile-butadiene
rubber and/or polymerizable comonomers such as vinyl compounds.
This additional adhesive is preferably present in a quantity of
less than 20 wt. %, preferably 0-10 wt. %, more preferably 0-5 wt.
% and in particular about 0-3 wt. %, each based on the total weight
of the textile fabric.
[0024] In principle however, it is conceivable for the fabric to
contain an adhesive. This can be present to strengthen the
nonwoven. For this, water-insoluble binders, for example
polyacrylates, styrene-butadiene rubber or nitrile-butadiene rubber
are advantageously used. From the prior art, it is known that for
the use of super-absorbers in powder form, adhesive is additionally
necessary for anchoring the powder on the textile fabric.
Water-soluble polymeric binders, for example polyvinyl alcohol, are
advantageously used for this in order to ensure the swellability of
the super-absorber. With the concept according to the invention,
the use of such an additional adhesive can be omitted. According to
a preferred embodiment of the invention, the fabric according to
the invention contains a proportion of water-soluble binders of
less than 20 wt. %, preferably 0-10 wt. %, more preferably 0-5 wt.
% and in particular about 0-3 wt. %, each based on the total weight
of the textile fabric.
[0025] Practical experiments have shown that the absorbent retains
its high strength even in the wet state (high gel strength). It is
surmised that the good anchoring of the gel is at least partially
caused by the high air permeability and open porosity of the
textile fabric. Namely, this enables large area bonding of the
absorbent. This is very advantageous, since under a hydrostatic
pressure wedge, little gel transport takes place and the damage
site can thus be spatially restricted to a small cable section.
Moreover, it was found that on damage to the cable, the absorbent
is only washed out to a slight extent.
[0026] Because of the particularly good sealing action of the
textile fabric according to the invention, the application of the
polymerizable mixture can also take place in the form of flat
swatches, for example in the form of strips, by printing or
spraying of the textile layer and the material usage can thus be
markedly reduced, which decreases the weight of the cable
overall.
[0027] In comparison to coatings containing absorbents, the use of
a porous textile layer as base material results in the following
advantages: The polymerization in the layer results in complete
penetration of the matrix material, which results in strong bonding
and low abrasion.
[0028] The textile layer displays a large surface area, which is
decisive for rapid blocking. Particularly suitable for this are
base materials which per se exhibit high air permeability or open
porosity, e.g. chemically bonded or water jet-strengthened
nonwovens. Thin, thermally strengthened nonwovens are in principle
also suitable. However, they often display a rather compact surface
structure which is difficult to endow with absorbent, so that a
flat surface coating is instead obtained.
[0029] Compared with the use of absorbents in powder form on
nonwovens, further advantages are found. Thus no additional
polymeric binder has to be used for immobilizing the powder, which
can impair the swellability of the material. Because of the firm
binding of the absorbent into the matrix material, no covering
layer has to be used in order to avoid powder abrasion. Because of
the higher strength of the absorbent, at the same time a higher
stability of the absorbent in the dry and wet state against
chemical and thermal degradation is achieved. The introduction of
additives, e.g. carbon black, fiber pulp, etc., into the absorbent
is directly possible during production. The textile fabric is
swellable on both sides. No gel blocking behavior occurs. Rather,
the absorbent is freely swellable.
[0030] According to the invention, it has been found that because
of the firm bonding of the absorbent material within the layer, the
absorption capacity of the absorbent material is restricted and the
pores can close in a self-sealing manner. The closure or
self-sealing takes place in such a manner that because of its
swelling the absorbent material completely or partially fills the
pores and seals these against the passage of liquids and/or gases,
preferably against the passage of water.
[0031] The textile fabric is further characterized by a tensile
strength in the machine direction (MD) of more than 50 N/5 cm. This
is advantageous, since a certain strength is necessary for the
cable production process, in which the materials are applied for
example as a wrapping. In principle, however, the tensile strengths
can be adjusted to preferred values depending on the particular use
purposes, for example from 80 to 1500 N/5 cm and/or from 100 to
1500 N/5 cm and/or from 150 to 800 N/5 cm, measured according to
DIN ISO 9073-3. A high tensile strength is very advantageous for
cable production, since the materials are as a rule applied under
tensile stress, for example as a wrapping. According to a preferred
embodiment of the invention, the textile fabric already has the
aforesaid high tensile strengths in the machine direction at low
thicknesses, for example less than 3 mm such as for example in the
range from 0.1 mm to 2 mm.
[0032] The textile fabric can be manufactured in a variety of
thickness ranges. This enables the use of a made-to-measure textile
fabric with regard to a wide variety of applications. Thus for
example the textile fabric can have thicknesses in the range from
0.1 to 3 mm, or 0.1 to 2 mm. For applications wherein the
construction space or the available room is limited, the textile
fabric must not lead to a marked increase in the cable diameter. In
these cases, thicknesses of less than 1 mm, for example from 0.1 mm
to 0.8 mm, or from 0.2 mm to 0.6 mm, measured according to DIN ISO
9073-2, are preferred. In certain cable applications, the textile
fabric can additionally take on the function of a padding layer.
Then thicknesses between 1.0 mm and 3.0 mm, for example 1.1 to 2.0
mm, or 1.2 to 1.8 mm, are preferred.
[0033] According to the invention, an absorbent material should be
understood to mean a swellable, preferably liquid-swellable, in
particular water-swellable material, which preferably can absorb at
least about 10 times, in particular about 20 times and preferably
about 30 times or more times its own weight in fluid. The absorbent
material according to the invention is in principle suitable for
the absorption of any liquids, such as in particular water, aqueous
salt solutions, rainwater, seawater, ground water and/or
condensation water. The absorbent material is preferably
water-insoluble.
[0034] Because of the firm bonding, the absorbent material is
securely located in the layer. Preferably, the layer according to
the invention is a textile layer. This enables simple processing of
the textile fabric during cable production.
[0035] Advantageously, because of the firm bonding, a single layer
structure is possible. Furthermore, it is advantageous that the
textile fabric because of its single layer structure is
particularly flexible and movable and has a low thickness.
[0036] A further advantage is that the absorbent material layer
stabilizes the textile layer and no additional reinforcing
component is necessary.
[0037] The absorbent material can be used as an adhesive.
[0038] In addition, the variable adjustment of the quantity of
absorbent material enables regulation of the absorbent capacity of
the textile layer for liquid. Thereby, an optimal blocking behavior
in the cable can be achieved and the weight and volume increase can
be minimized with suitable adjustment.
[0039] Preferably, fibers of the layer are partially or completely
coated with the absorbent material. Thereby, the absorbent material
is applied onto the surface of the fibers as a firmly adhering
layer. A coating can be a thin or thick layer, which continuously
and cohesively surrounds or encloses the fibers. This enables good
adhesion between the absorbent material and the fibers of the
layer. Further, the thickness of the layer of absorbent material
can be optimally adjusted.
[0040] The formation of a coating on the surface of the fabric
itself is to be differentiated from the coating of the individual
fibers. According to the invention, the formation of such a coating
is in fact of little advantage if thereby the air permeability or
open porosity of the fabric is reduced below the degree desired
according to the invention. As discussed above, this in fact has an
adverse effect on the swelling behavior of the absorbent.
[0041] Hence, the problem stated at the outset has been solved.
[0042] The absorbent material can be present free of coating, that
is to say, the absorbent material is not covered or enclosed by a
covering layer. This enables rapid liquid absorption, since no
passage of the liquid through the supporting or covering layer is
involved.
[0043] The absorbent material used according to the invention on
contact with liquid is capable of sealing the pores on account of a
shape change, in particular a swelling and volume increase.
[0044] The textile layer could be constituted as fleece, nonwoven,
fabric, knitted material and/or woven material. Thereby, a textile
fabric with a particularly flat structure is obtained, and the
textile fabric is easily deformable. This facilitates further
processing of the textile fabric.
[0045] According to the invention, a nonwoven is preferably used.
The use of a nonwoven is particularly preferred according to the
invention. The fleece laying can be effected dry in a carding
process or in a wet fleece process. Preferably the fleece laying
takes place in such a manner that in the fleece a higher proportion
of the fibers is oriented in the longitudinal direction (machine
direction) than in the transverse direction (longitudinally laid
fleece). This is advantageous since higher tensile strengths in the
longitudinal direction can be achieved. To increase the tensile
strengths, reinforcing threads could alternatively or additionally
also be incorporated in the longitudinal direction. The
reinforcement could be effected mechanically, chemically and/or
thermally. Mechanical reinforcement can be effected by needlework
techniques or by intertwining fibers of the layer by means of water
jets and/or air. For cable applications, nonwovens of low thickness
and high tensile strength are needed. Hence, reinforcement by means
of needlework techniques appears rather disadvantageous for the use
according to the invention in cable production.
[0046] In chemically bonded nonwovens, a fiber gauze could be
provided with an adhesive or with the mixture used for the
production of the textile fabric according to the invention by
impregnation, spraying or by otherwise conventional application
methods. Thereby, a sufficiently strong product with a high tensile
strength can be produced, which is advantageous for the use
according to the invention in cable products.
[0047] According to a preferred embodiment, the textile layer
contains fibers selected from the group consisting of polyolefins,
in particular polyphenylene sulfide, polyester, in particular
polyethylene terephthalate, polybutylene terephthalate, polyamide,
in particular polyamide 6.6 (Nylon.RTM.), polyamide 6
(Perlon.RTM.), polyvinyl chloride, polyacrylonitrile, polyimide,
polytetrafluoroethylene (Teflon.RTM.), aramid, wool, cotton, silk,
hemp, bamboo, kenaf, sisal, cellulose, soya, flax, glass, basalt,
carbon or viscose fibers and mixtures thereof.
[0048] Particularly preferably, the textile layer contains fibers
selected from the group consisting of polyethylene, polypropylene,
polyamide, poly-p-phenylene terephthalamide, poly-m-phenylene
terephthalamide, polyester, cotton or viscose fibers and mixtures
thereof. Because of its good mechanical properties, thermal
stability and low cost, polyester, and in particular polyethylene
terephthalate, is particularly preferred according to the
invention.
[0049] According to the invention, the textile layer has pores. The
pores could be formed by pores which are present in the layer
especially on the basis of the fiber structure. According to the
invention, the textile fabric has a porosity according to ISO
8971-4 in the range from 50 to 95%, in particular in the range from
80 to 90%. Preferably, the fabric has a pore distribution with a
smallest pore diameter from 2 to 20 micrometers, and/or an average
pore diameter from 10 to 150 micrometers and/or a greatest pore
diameter from 50 to 500 micrometers, measured according to ASTM E
1294-89, with galden as the measurement liquid and by means of a
capillary flow porometer CFP-1200-AEXL.
[0050] It is further possible that the pores can be introduced by
the formation of recesses and/or channels. As a result of the
pores, after liquid uptake the absorbent material can extend in a
spatially limited manner corresponding to the geometry of the pores
and the weight and volume uptake of the textile fabric can be
varied.
[0051] The pores could be randomly distributed. This enables rapid
liquid uptake into the layer. Preferably, a local liquid uptake
takes place within the ventilation aperture directly at the
penetration site of the liquid.
[0052] Further, the pores could have a random geometric structure.
As a result, capillary effects occur which lead to very rapid
liquid uptake in the layer.
[0053] The weight per unit area can vary over wide ranges.
Preferably, the textile fabric has a weight per unit area according
to DIN EN 29073-1 from 20 to 400 g/m.sup.2, preferably from 20 to
300 g/m.sup.2, in particular from 30 to 250 g/m.sup.2. Fabrics
according to the invention with such weights per unit area have
outstanding stability.
[0054] The textile fabric could contain no additionally introduced
hydrophilic fibers, for example based on polyvinyl alcohol,
polyacrylic acid, polyvinyl acetate or cellulose. The proportion of
hydrophilic fibers additionally introduced based on the total
weight of the textile fabric could be less than 100 wt. %,
preferably less than 50 wt. %, especially preferably less than 25
wt. % and in particular 0 wt. %.
[0055] The textile fabric can be used as such as a sealing element
in and/or around cables. For many use purposes, however, it can be
advantageous to form the fabric as a composite material, for
example as a laminate in combination with supporting and/or
protective layers in the form of textiles, sheets or papers.
[0056] The invention also comprises a method for producing the
textile fabric according to the invention, comprising the following
method steps: [0057] a) treating a layer containing pores with a
mixture containing a polymerizable monomer or oligomer and a
cross-linking agent, as precursor for the absorbent material, a
wetting agent and an initiator, and [0058] b) polymerizing the
monomer or oligomer to the absorbent material with formation of an
at least partially bonded connection between the absorbent material
and the layer.
[0059] Surprisingly, it was found that through the use of a wetting
agent, a surface tension of the mixture is influenced in such a
manner that a bonded connection of the absorbent material with the
layer takes place and the absorbent material is securely bonded
with the layer. At the same time, the textile fabric is endowed
with high air permeability and open porosity. As already described
above, this high air permeability and open porosity results in good
anchoring of the absorbent both in the dry and also in the wet and
thus swelled state, which results in surprisingly effective
blocking of further water transport in the longitudinal direction
of the cable.
[0060] Advantageously, the use of a glue, adhesive and/or bonding
agent for the bonding of the absorbent material with the layer is
not necessary. As a result of this, an additional method step,
namely fixing of the absorbent material with the layer, can be
omitted. Thermal fixing of the absorbent material is also not
necessary.
[0061] With the method according to the invention, the absorbent
material can be introduced directly into the textile layer and
bonded therewith. As a result, targeted control of the liquid
absorption and swelling of the absorbent material takes place and
self-sealing closure of the pores within the layer.
[0062] A further advantage of the method according to the invention
is that because of the polymerization, the absorbent material has
good adhesion within the layer and the textile fabric produced
according to the method is characterized by elevated abrasion
resistance.
[0063] According to the invention, a wetting agent is understood to
mean natural or synthetic substances which in solution or in
mixtures lower the surface tensions of water or other liquids, so
that these can better penetrate into surfaces of solid bodies, such
as the layer, and with displacement of air can impregnate and wet
them.
[0064] A wetting agent is preferably selected from the group
consisting of: glycerin, propylene glycol, sorbitol,
trihydroxystearin, phenol, acid resin, phospholipids, ethylene
oxide/fatty alcohol ethers, ethoxylates of propylene oxide with
propylene glycol, esters of sorbitol and glycerin and mixtures
thereof.
[0065] Particularly preferably, a compound of the following
formula
RO(CH.sub.2CH.sub.2O).sub.xH,
is used as the wetting agent, wherein R is a linear or branched
alkyl residue and wherein x=4, 5, 6.3, 6.5, 7, 8, 9, 10 or 11,
preferably 6.5, 7, 8, 9 or 10, in particular 6.5, 7, 8 or 9.
Practical experiments have shown that with the use of such a
wetting agent the surface tension of the mixture is particularly
effectively lowered, as a result of which the penetration of the
mixture into the textile layer is facilitated. This results in
excellent adhesion between the absorbent material and the
layer.
[0066] According to the invention, an alkyl residue is a saturated,
aliphatic hydrocarbon group with 1 to 30, preferably 3 to 20, more
preferably 4 to 17 and in particular 6 to 11 carbon atoms. An alkyl
group can be linear or branched and is optionally substituted with
one or several aliphatic, in particular saturated, hydrocarbon
groups with 1 to 4 hydrocarbons.
[0067] Practical experiments have shown that with a content of the
wetting agent based on the total quantity of the mixture in the
range from 0.1 to 5 wt. %, preferably from 1 to 4 wt. %, in
particular from 1.5 to 3.5 wt. %, particularly uniform and
homogeneous wetting of the layer takes place.
[0068] Particularly good results as regards the wetting of the
layer were achieved with the addition of a wetting agent which sets
a surface tension according to DIN 55660 of the mixture in the
range from 10 to 72 dyn, preferably in the range from 15 to 60 dyn,
in particular in the range from 20 to 68 dyn.
[0069] Cross-linking comprises reactions in which a large number of
individual macromolecules are linked into a three-dimensional
network. The linking can be achieved either during the building of
the macromolecules or by reactions on already existing
polymers.
[0070] Through the cross-linking process, the properties of the
cross-linked substances can change. The change increases with an
increasing degree of cross-linking. The degree of cross-linking is
a quantitative measure for the characterization of polymeric
networks. The degree of cross-linking is calculated as the quotient
of a mole number of cross-linked basic building blocks and a mole
number of basic building blocks in total present in the
macromolecular network. It is stated either as a dimensionless
number or in percent (mass proportion).
[0071] The cross-linker used according to the invention binds or
cross-links the monomers or oligomers together in places by
chemical bridges. This bridge formation can decrease the water
insolubility of the absorbent material. On penetration of liquid
into the absorbent material, this swells up and tightens this
network at the molecular level--the pores close and seal
themselves. As a result, penetration or passage of liquid through
the pores can be prevented.
[0072] The cross-linker used in the method according to the
invention advantageously has at least two reactive functional
groups, which can react with functional groups of the polymerizable
monomers or oligomers during the polymerization.
[0073] Advantageously, the cross-linker has at least one olefin,
carboxyl, and/or carboxylate group. The cross-linkers are
preferably selected from the group consisting of:
[0074] ethylene glycol bisacrylate, diethylene glycol
dimethacrylate, polyethylene glycol dimethacrylate, propylene
glycol dimethacrylate, polypropylene glycol dimethacrylate,
tetramethylolmethane trimethacrylate, N-methylolacrylamide,
glycerin trimethacrylate, glycidyl methacrylate,
N,N'-methylenebismethacrylamide, diallyl maleate, diallyl
phthalate, diallyl terephthalate, triallyl cyanurate, triallyl
isocyanurate, triallyl phosphate, dipentaerythritol hexaacrylate,
polyethylene glycol diglycidyl ether, di- or polyglycidyl ethers of
aliphatic, polyvalent alcohols, ethylene glycol glycidyl ether,
myrcene and mixtures thereof.
[0075] Particularly preferred cross-linkers are triethylene glycol
dimethacrylate, ethylene dimethacrylate, 1,1,1-trimethylpropane
triacrylate, 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione,
1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate,
ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate,
N,N'-methylene-diacrylamide and mixtures thereof. These
cross-linkers are particularly suitable for targeted control of the
absorption capacity of the absorbent material, so that only a small
liquid uptake is necessary for the sealing of the pores.
[0076] A degree of cross-linking in the range from
4.7.times.10.sup.-5 to 1.9.times.10.sup.-1, preferably from
2.3.times.10.sup.-4 to 1.3.times.10.sup.-1, in particular from
4.7.times.10.sup.-4 to 4.9.times.10.sup.-2, is preferably set.
Through a high degree of cross-linking, the absorption capacity of
the absorbent material is limited and the pores become closed with
low liquid absorption.
[0077] According to a preferred embodiment of the invention, the
proportion of the cross-linker based on the total quantity of the
monomer content is 0.1 to 40.00 wt. %, preferably 0.05 to 28.00 wt.
%, in particular 0.10 to 20.00 wt. %. With such a cross-linker
content, the absorbent capacity of the absorbent material is high
enough to be able to close the pores optimally and as rapidly as
possible on contact with a liquid.
[0078] According to a further preferred embodiment, the
polymerizable monomer or oligomer is selected from the group
consisting of: monoethylenically unsaturated mono-carboxylic acids,
in particular acrylic acid, methacrylic acid, maleic acid, fumaric
acid, crotonic acid, sorbic acid, itaconic acid and cinnamic acid;
monoethylenically unsaturated polycarboxylic acid anhydrides, in
particular maleic anhydride; carboxylic acid salts, preferably
water-soluble salts, in particular alkali metal, ammonium or amine
salts; monoethylenically unsaturated mono- or polycarboxylic acids,
in particular sodium meth-, trimethylamine meth-, triethanolamine
meth-, sodium maleate, methylamine maleate; sulfonic acids,
preferably aliphatic or aromatic vinylsulfonic acids, in
particular, vinyl, allyl, vinyltoluene, styrene or
methacrylsulfonic acids; 2-hydroxy-3-methacryloxypropylsulfonic
acid; sulfopropyl methacrylate, sulfonic acid salts, preferably
alkali metal, ammonium or amine salts of sulfonic acid
group-containing monomers or oligomers; hydroxy compounds,
preferably monoethylenically unsaturated alcohols,
monoethylenically unsaturated ethers or esters of polyols, in
particular methylallyl alcohol, alkylene glycols, glycerin,
polyoxyalkylene polyols, hydroxyethyl methacrylate, hydroxypropyl
methacrylate, triethylene glycol methacrylate, polyoxyethylene
propylene glycol monomethyl allyl ether, wherein the hydroxy groups
are optionally etherified or esterified; amides, preferably
monoethylenically unsaturated vinylform-, acryl-, methacryl-,
N-alkylmeth-, N,N-dialkylmethacryl-, N-hydroxyalkylmethacryl-,
N-hexylacryl-, N,N-dimethylacryl-, N,N'-di-n-propylacryl-,
N-methylolmethacryl-, N-hydroxyethylmethacryl-, and
N,N-dihydroxyethylmethacrylamide, vinyl lactams, in particular
N-vinylpyrrolidone; amino compounds, preferably amino
group-containing esters, monoethylenically unsaturated mono- or
dicarboxylic acids, heterocyclic vinyl compounds, in particular
dialkylaminoalkyl-, dihydroxyalkylaminoalkyl- or morpholinoalkyl
esters; vinylpyridines, in particular 2-vinyl-, 4-vinyl- or
N-vinylpyridine, or N-vinylimidazole; quaternary ammonium salts,
preferably N,N,N-trialkyl-N-methacryloyloxyalkylammonium salts, in
particular N,N,N-trimethyl-N-methacryloyloxyethylammonium chloride,
N,N,N-triethyl-N-methacryloyloxyethylammonium chloride,
2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride, in
particular dimethylaminoethyl methacrylate, diethylaminoethyl
methacrylate, morpholinoethyl methacrylate, dimethylaminoethyl
fumarate and mixtures thereof. Preferred according to the invention
are acrylic acid, methacrylic acid, amides and vinylsulfonic acids
and mixtures thereof.
[0079] Advantageously, the content of the monomer or oligomer based
on the total quantity of the mixture is 3 to 80, preferably 5 to 70
wt. %, in particular 10 to 50 wt. %. Practical experiments have
found that with this monomer or oligomer content the absorbent
capacity of the absorbent material, in particular of water, is
sufficiently high and the textile fabric is particularly
stable.
[0080] According to the invention, substances which are added to
the mixture containing monomers or oligomers and wetting agents in
order to enable and to start or to initiate the desired
polymerization are described as initiators.
[0081] Advantageously, water-soluble azo compounds, redox systems,
peroxycarboxylic acids, peroxycarboxylic acid esters, thioxanthene,
thioamines, ketone peroxides, hydroperoxides, dicarbonates,
oxalates, nitriles, preferably valeronitrile, anisoins,
benzophenones, acetophenones, anthraquinones, benzene chromium
tricarbonyls, benzoins, benzoin ethers, benzils, benzil ketals,
4-benzoylbiphenyls, phenylpropanediols, cyclopentadienyliron(II)
cumene hexafluorophosphates,
10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5-ones,
diphenyl(2,4,6-trimethylbenzoyl)phosphine oxides,
2-hydroxy-2-methyl-propiophenones, 4'-ethoxyacetopheones,
ethylanthraquinones, 1-hydroxycyclohexyl phenyl ketones,
2-methyl-4'-(methylthio)-2-morpholinopropiophenones,
phenanthrenequinones, 4-phenoxyacetophenones, triarylsulfonium
hexafluoroantimonates in propylene carbonate, triarylsulfonium
hexafluorophosphate salts in propylene carbonate, .alpha.-hydroxy
ketones, phenyl glyoxylates, benzyl dimethyl ketals,
.alpha.-aminoketones, 2,5-dimethyl-2,5-dihydroperoxy-hexane,
1,3-di-(2-hydroperoxyisopropyl)-benzene, monoacylphosphines,
bisacylphosphines, phosphine oxides, metallocenes, peroxides,
persulfates, permanganates, chlorites, cerium salts, iodine salts
and/or hypochlorites are used as initiators; preferably
2,2'-azobis[2-(2-imidazolin-2-yl)propane dihydrochloride,
azobis(2-amidinopropane) dihydrochloride, azo-bis-cyanopentanoic
acid, 4-benzoyl-N,N,N-trimethylbenzenemethanaminium chloride,
2-hydroxy-3-(4-benzoylphenoxy)-3-N,N,N-trimethyl-1-propanaminium
chloride monohydrate,
2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthon-2-yloxy)-N,N,N-trimethyl-1-
-propanaminium chloride,
2-hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone,
2-hydroxy-2-methyl-1-phenylpropan-1-one,
4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyl)oxy]ethylbenzene-methanamin-
ium chloride,
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one,
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile),
anthraquinone-2-sulfonic acid sodium monohydrates,
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxides,
dibenzenechromium, benzoamines, benzoin ethyl ether, benzoin methyl
ether, benzoin isobutyl ether, 3,3',4,4'-benzophenonetetracarboxyl
dianhydride, 4-phenylbenzophenone,
2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone,
4,4'-bis(diethylamino)benzophenone,
4,4'-bis(dimethylamino)benzophenone, 4,4'-dimethylbenzil,
2,5-dimethylbenzophenone, 3,4-dimethylbenzophenone,
3'-hydroxyacetophenone, 4'-hydroxyacetophenone,
3-hydroxybenzophenone,
.alpha.,.alpha.-dimethoxy-.alpha.-phenylacetophenone,
4-hydroxybenzophenone, 2-methylbenzophenone, dialkoxyacetophenones,
.alpha.-hydroxyalkylphenones, .alpha.-aminoalkylphenones,
4,4'-dihydroxybenzophenones, 2,2-dimethoxy-2-phenylacetophenone,
4-(dimethylamino)benzophenone, 3-methylbenzophenone,
1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone,
2-hydroxy-2-methylpropiophenone, 4-dimethylaminobenzophenone,
2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxy-acetophenone,
methyl benzoylformate, hydroxyphenylacetic acid
2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl ester, hydroxyphenylacrylate
2-[2-hydroxy-ethoxy]ethyl ester, 2-chlorothioxanthene-9-ones,
2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone,
2-methyl-1-[4-(4-morpholinophinyl)1-propanone,
diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide,
phenyl-bis-(2,4,6-trimethyl)-benzoylphosphine oxide, ferrocene,
titanocene,
bis-.eta..sup.5-2,4-cyclopentadien-1-yl)-bis-[2,6-difluoro-3-(1H-pyrro-1--
yl)-phenyl]titanium,
(4-methylphenyl)-[4-(2-methylpropyl-(4-methylphenyl)-[4-(2-methylpropyl)p-
henyl]-iodonium hexafluorophosphate, ammonium persulfate, potassium
persulfate, camphorquinone, cymene cyclopentadienyliron
hexafluorophosphate, dibenzocycloheptadienone,
hydroxyacetophenones, thioxanthen-9-ones, 4,4'-dimethylbenzil,
2-ethylanthraquinone, acrylphosphine oxide, 2-methylbenzoyl
formate, didecanoyl peroxide, dilauryl peroxide, dibenzoyl
peroxide, di-(2-ethyl)-peroxydicarbonate, dicyclohexyl
peroxodicarbonate, di-(4-tert.-butyl)-cyclohexyl peroxydicarbonate,
diacetyl peroxodicarbonate, dimyristyl peroxodicarbonate,
di-tert.-butyl peroxyoxalate,
2,2-azobis(2,4-dimethylvaleronitrile),
2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile),
2,2'-azobis(2-methylbutyronitrile),
2,2'-azobis(N-(2-propenyl)-2-methylpropionamide,
dimethyl-2,2'-azobis(2-methylpropionate), dimethyl
2,2'-azoisobutryrate, 1-hydroxy-cyclohexyl phenyl ketones,
peroxycarboxylic acid esters, produced from pivalic acid,
neodecanoic acid, 2-ethylhexanoic acid, tert-butyl hydroperoxide,
tert.-amyl hydroperoxide, and/or cumene hydroxide, tert.-amyl
hydroperoxide, cumene hydroperoxide, diacyl peroxide, hydrogen
peroxide, 2-di(3,5,5-trimethylhexenoyl) peroxide, hydroxy and/or
tert.-butyl peroxide, in particular
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxides,
1-hydroxycyclohexyl phenyl ketones, benzophenones and/or
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-ones
are used as initiators.
[0082] The content of the initiator based on the total quantity of
the mixture could lie in the range from 0.1 to 3 wt. %, preferably
from 0.5 to 2 wt. %, in particular from 0.7 to 1.5 wt. %.
[0083] Depending on the use field, the mixture could contain a
filler. Fillers increase the volume or weight and can improve the
technical properties of the mixture. The filler is preferably
selected from the group consisting of: carbonates, in particular
calcium carbonate, carbon blacks, in particular conductive carbon
black, graphite, ion exchange resins, activated charcoals,
silicates, in particular talc, clay, mica, silica, zeolites, chalk,
calcium and barium sulfate, aluminum hydroxide, glass fibers and
beads and wood flour, cellulose powder, perlite, cork or plastic
granules, ground thermoplastics, cotton or carbon fibers, in
particular ground carbon fibers and mixtures thereof. Through the
addition of a filler, the permeability for liquid and/or air can be
varied and the thermal and/or electrical conductivity of the
material controlled.
[0084] In addition, the mixture could contain disinfectants,
antioxidants, comonomers, anticorrosion agents, in particular
triazoles and/or benzimidazoles, thickeners, foaming additives,
defoamants, fragrances and/or active substances.
[0085] Through the polymerization from the monomers or oligomers
performed in method step b), a super-absorber could be formed.
Super-absorbers are characterized in that they can outstandingly
bind and absorb liquid. According to the invention, a
super-absorber is understood to be a polymer which is capable of
taking up or absorbing a multiple of its own weight, up to 500
times, of liquids, preferably water, whereby it increases in
volume.
[0086] To form the mixture, the monomer or oligomer is dissolved or
emulsified, preferably in an aqueous solution. The water content in
the mixture could lie in the range from 20 to 90 wt. %, preferably
in the range from 30 to 80 wt. %, each based on the total quantity
of the mixture. If the cross-linker is not soluble, it can be added
in emulsified form. In addition, an organic solvent miscible with
water can be added to dissolve or disperse the cross-linker. Next,
the wetting agent and the initiator could be added.
[0087] The polymerization preferably takes place in the acidic pH
range from 3 to 6, in particular from 4.3 to 5.5. Under these
conditions the mixture is particularly stable.
[0088] To neutralize the acrylic acid monomer or the aforesaid
acidic monomers or oligomers, a hydroxide, preferably an alkali
metal hydroxide, in particular sodium, potassium or lithium
hydroxide, carbonate of an alkali metal and/or ammonium hydroxide
could be used. Because of their commercial availability, their
price and their safety, sodium or potassium hydroxide are
particularly preferably used.
[0089] The treatment of the layer with the mixture could be
effected by impregnation, printing, coating and/or spraying. It is
essential in the selection of the application method and setting of
the particular process parameters that the air permeability and
open porosity to be set according to the invention can be attained
therewith. Conventional coating methods are blade coating and kiss
coating. In blade coating, a coating blade usually operates against
an underlay, roller, bench or the substrate itself. A coating blade
is understood to mean a coating device. This could be fixed over
the whole width of the fabric web. The application of the mixture
can be effected with the following coating knives (coating blades):
roller blade, air blade, rubber mat blade, support blade, bench
blade, spiral blade and/or box-type coating bar. In kiss coating, a
printing roller with a smooth surface or with etched, mechanically
processed or knurled indentations on the surface is normally used.
The mixture could be transferred from the printing roller onto the
fabric to be coated. The indentations can have any desired size or
shape and be discontinuously or continuously distributed on the
surface of the printing roller.
[0090] The application of the mixture by impregnation is
particularly preferred, in particular by foularding or by foam
impregnation. The foularding can be performed in a single step or
multiple steps, wherein a defined mixture is applied uniformly per
m.sup.2 textile material. In foularding, a liquor is pressed into a
textile fabric by roller pressure. The term liquor here designates
the entirety of all its components, that is the solvent, preferably
water, and all dissolved, emulsified or dispersed constituents
contained therein such as dyes, particles, pigments, chemicals and
additives.
[0091] The quantity of the mixture applied for the impregnation,
coating or spraying of the layer can vary in a wide range. Usually
quantities in the range from 10 to 2500 g/cm.sup.2, in particular
from 50 to 1200 g/cm.sup.2 are incorporated into the fiber
structure of the layer.
[0092] After the impregnation, coating or spraying, the layer can
be squeezed out between two rollers and/or cylinders. Practical
experiments have shown that with a squeezing pressure in a range
from 0.5 to 8 bar, preferably in a range from 1 to 3 bar, the
quantity applied can be optimally set and a homogeneous
distribution of the mixture applied in the fiber structure of the
layer takes place.
[0093] Then, in a next step, the polymerization or curing of the
monomers or oligomers can take place, as a result of which the
absorbent material is formed. Depending on the initiator used and
the reaction conditions, the polymerization can be initiated
autocatalytically, thermally, by the action of ionizing radiation
or by means of plasma. The monomer or oligomer is preferably
polymerized in presence of ultraviolet radiation.
[0094] UV curing could be effected using a UV lamp. Irradiation
intensity and time are based on the composition of the mixture and
the state of the layer. Particularly good results are achieved with
an irradiation intensity in the range from 40 to 400 watt/cm,
preferably in the range from 100 to 250 watt/cm with an irradiation
time in the range from 0.1 to 120 seconds. The UV curing is
advantageously performed under vacuum or in the presence of an
inorganic gas, preferably nitrogen, helium or argon, or in air.
[0095] Thermal curing could take place in an oven, in air or in an
inert atmosphere or under vacuum. It is also possible to polymerize
or to cure the applied mixture in a dryer, such as a tunnel dryer
or an infrared dryer. Usually, the polymerization or curing takes
place in a temperature range from 40 to 100.degree. C.
[0096] Against this background, it is also conceivable to use
electron beams to cure the mixture. Usually curing takes place at
an energy dosage in the range from 1 to 16 megarad, preferably in
the range from 2 to 8 megarad.
[0097] Following polymerization, the treated textile fabric can be
subjected to one or more washing steps. Thereby, impurities, for
example unconverted monomer, uncross-linked polymer, additives or
auxiliary agents and initiator residues can be removed from the
textile fabric. Washing is preferably effected with water and can
be take place continuously or discontinuously. Practical
experiments have shown that the sealing action can be increased by
the washing process. It is surmised that the observed increase in
the sealing action is due to an averaging of the pore structure
and/or reorganization of the fiber structure.
[0098] According to a preferred embodiment, a neutralization step
takes place following the polymerization. For this, the textile
fabric could be passed through a neutralization bath with a pH in
the range from 9 to 14, preferably in the range from 10 to 14, in
particular in the range from 12 to 14.
[0099] For the neutralization, the hydroxides already previously
mentioned, preferably alkali metal hydroxide, in particular sodium,
potassium or lithium hydroxide, carbonate of an alkali metal and/or
ammonium hydroxide, can be used.
[0100] After curing or polymerization, the residual liquid could be
removed by further drying in the air circulation oven or with
infrared lamps. According to the invention, drying is preferably
performed by contactless energy input (contactless drying). Here,
contactless drying is understood to mean that the energy transfer
does not take place via direct contact with a heat-transferring
material (for example heated rollers), but rather contactless, for
example via radiation, preferably infrared or microwave radiation
and/or via hot air as heat-transfer medium, in particular
circulating air or ventilation air. Contactless drying has been
found advantageous since a sealing of the surface caused by the
direct contact with a heat-transfer material can be avoided.
Usually, drying temperatures in the range from 60.degree. C. to
180.degree. C. have been found suitable for most materials.
[0101] It is also conceivable to subject the textile fabric to a
subsequent treatment or finishing of a chemical nature, such as for
example an anti-pilling treatment, hydrophilization, an antistatic
treatment, a treatment to improve fire resistance and/or to alter
the tactile properties or the gloss, a treatment of a mechanical
nature such as roughening, sanforizing, smoothing or a treatment in
the tumbler and/or a treatment to change the appearance such as
dyeing or printing. Further, for many use purposes it can be
advantageous subsequently to treat or provide the textile fabric
with one or more additives, for example selected from carbonates,
in particular calcium carbonate, carbon blacks, in particular
conductive carbon black, graphites, ion exchange resins, activated
charcoals, silicates, in particular talc, clay, mica, silica,
zeolites, chalk, calcium and barium sulfate, aluminum hydroxide,
glass fibers and beads and wood flour, cellulose powder,
super-absorber in powder form, perlite, cork or plastic granules,
ground thermoplastics, cotton or carbon fibers, in particular
ground carbon fibers and mixtures thereof. Through the addition of
a filler and/or additive, for example the permeability for liquid
and/or air can be varied and the thermal and/or electrical
conductivity of the material controlled. To improve the adhesion of
the additive and/or filler, an adhesive can be used, for example
based on polyvinyl alcohol, polyacrylates, polyurethanes,
styrene-butadiene rubber or nitrile-butadiene rubber.
[0102] On account of its ability effectively to prevent the
spreading of water along the longitudinal axis of the cable, its
low weight and its high flexibility, the textile fabric according
to the invention is outstandingly suitable as a sealing element in
and/or around cables, for example (power-conducting underground and
undersea cables) of a wide variety of voltage ranges. According to
a particularly preferred embodiment of the invention, the textile
fabric is present in the cable as a wrapping or bandage. According
to a particular embodiment of the invention, the textile fabric is
used as a sealing element of cavities in the conductor area and/or
shielding area and/or in the area of the sheathing of cables.
[0103] Thus the fabric according to the invention for cables can be
used for example in the shielding area--above and/or below the
shielding components (for example metal (copper or aluminum) wires,
sheets, tapes and metal sheaths). This embodiment is particularly
advantageous with cables in the middle voltage range (1 to 1150
kV).
[0104] According to a further preferred embodiment, the fabric is
used in the conductor area of cables. Thus for example the
positioning of the fabric is in the segmented conductor, as
sheathing of the conductor segments, in the conductor segments, as
sheathing of the whole conductor, cut into tapes and/or spun into a
yarn as sealing along the open channels in the conductor area. This
embodiment is particularly advantageous with cables in the high and
very high voltage range (60 to 1150 kV). In these cable types, the
fabric is advantageously additionally introduced in the shielding
area, for example above and below the screening components (metal
(copper or aluminum) wires, sheets, tapes and metal sheaths).
[0105] According to a further preferred embodiment of the
invention, the fabric is used as sheathing of individual cables,
cable bundles and of the conductor core or cut into tapes and/or
spun into a yarn as a sealant along the open channels in cable
bundles as a cable filling. This embodiment is particularly
preferred in data, signal, glass fiber and telecommunications
cables.
[0106] In undersea cables, the positioning within the sheathing is
possible as a further use area alternatively or preferably in
addition to the aforesaid use areas.
[0107] A preferred embodiment of the invention relates to the use
of a textile fabric according to the invention as a sealing element
of cavities in data, signal, glass fiber and telecommunications
cables and cables for power transmission. Use in cables for power
transmission is especially preferred.
[0108] A further preferred embodiment of the invention relates to
the use of a textile fabric according to the invention in band form
and/or spun into a yarn as sealing along the open channels in
individual cables, cable bundles and/or between cable layers and/or
as sheathing of individual cable layers.
[0109] A further preferred embodiment of the invention relates to
the use of a textile fabric according to the invention as a sealing
element of cavities in and/or over the conductor, over and/or under
the shielding, and in and/or over and/or under the sheathing of
cables for power transmission.
[0110] A further preferred embodiment of the invention relates to
the use of a textile fabric according to the invention above and/or
below the shielding component of cables and/or in the conductor
area as sheathing of the conductor core and/or one or more of the
conductor segments of a segmented conductor and/or within the
conductor core or the conductor segments, cut into tapes and/or
spun into a yarn as sealing along the open channels in the
conductor area.
[0111] FIG. 1 shows a textile fabric 1, comprising at least one
layer 2, which is at least partially covered by an absorbent
material 3 and has pores 4, wherein the pores 4 under the action of
liquid can at least partially be sealed because of swelling of the
absorbent material 3.
[0112] The absorbent material 3 is at least in some areas bonded to
the textile layer 2.
[0113] The pores 4 and the size of the pores 4 are statistically
randomly distributed. The geometric structure of the pores 4 is
random. The pores 4 are not regularly structured geometrical bodies
such as squares or octahedra, but are open-celled or closed
interstices which are separated from one another by fibers 5 or the
absorbent material 3.
[0114] The textile layer 2 consists of a chemically bonded
nonwoven.
[0115] The textile layer 2 in FIG. 1 contains polyester fibers
5.
[0116] The absorbent material 3 in FIG. 1 covers the fibers 5
essentially completely.
[0117] The textile fabric 1 in FIG. 1 has a thickness of 0.5
mm.
[0118] The textile fabric 1 in FIG. 1 has a weight per unit area of
100 g/m.sup.2.
[0119] FIG. 2 is a detailed view of the textile fabric 1 shown in
FIG. 1 in the dry state. This textile fabric 1 comprises at least
one layer 2, which is at least partially covered by an absorbent
material 3 and has pores 4, wherein the pores 4 under the action of
liquid can at least partially be sealed because of swelling of the
absorbent material 3. The absorbent material 3 is in some areas
bonded to the textile layer 2.
[0120] The fibers 5 of the layer 2 are completely covered or coated
with the absorbent material 3.
[0121] The ventilation aperture 4 shown in FIG. 2 is completely
opened.
[0122] FIG. 3 is a detailed view of the textile fabric 1 shown in
FIG. 1 under the action of liquid. The penetrating liquid is
absorbed by the absorbent material 3. The swelled absorbent
material 3 fills the ventilation aperture 4, shown in FIG. 2,
completely and seals this against the passage of liquid and/or a
gas.
[0123] FIG. 4 shows a textile fabric 1', comprising at least one
layer 2, which is at least partially covered with an absorbent
material 3 and has pores 4, wherein the pores 4 under the action of
liquid can at least partially be sealed because of a swelling of
the absorbent material 3.
[0124] The absorbent material 3 is at least in some areas bonded to
the textile layer 2.
[0125] The absorbent material 3 covers the fibers 5 partially.
[0126] The pores 4 are uniformly distributed in the layer 2.
[0127] The textile fabric 1', shown in FIG. 4, has a weight per
unit area of 100 g/m.sup.2.
[0128] FIG. 5 is a detailed view of the textile fabric 1' shown in
FIG. 4 in the dry state. The absorbent material 3 is in some areas
bonded to the textile layer 2.
[0129] The pores 4 are open.
[0130] FIG. 6 is a detailed view of the textile fabric 1' shown in
FIG. 4 under the action of water.
[0131] The water penetrating is absorbed by the absorbent material
3 with a volume increase. Through swelling of the absorbent
material 3, the ventilation aperture 4 is partially sealed.
[0132] The thickness of the textile fabric 1' shown in FIG. 4 has
increased 3-fold under the action of water.
[0133] FIG. 7 is a schematic representation of an example of a
layered structure of a cable for power transmission. Cable layer 1
is the conductor, which can be built up of individual wires or
conductor segments. As cable layer 2 in FIG. 7, a textile fabric
according to the invention is used as a sealing layer. Cable layer
3 is an insulating layer of polyethylene, which in the present case
is multilayer structured. As cable layer 4 in FIG. 7, a textile
fabric according to the invention is used as a sealing layer. Cable
layer 5 is the shielding. As cable layer 6 in FIG. 7, a textile
fabric according to the invention is used as a sealing layer. Cable
layer 7 is the cable sheathing. Not shown in the diagram is the
reinforcement. This could be positioned underneath the cable
sheathing.
[0134] The textile fabric thus described can be produced according
to the following practical examples:
Practical Example 1
[0135] For the production of a partially neutralized acrylic acid
solution, 8.00 g of sodium hydroxide are dissolved in 21.00 g water
and treated with 21.00 g of acrylic acid. Next 25.00 g of the
partially neutralized acrylic acid solution are homogeneously mixed
with 0.50 g of
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one,
1.00 g of heptyl polyethylene glycol ether
(C.sub.7H.sub.15O(CH.sub.2CH.sub.2O).sub.6.5H) and 47.00 g water.
The pH of the solution is ca. 4.
[0136] 0.25 g of N,N'-methylenediacrylamide are added to the
solution and this is stirred for 15 minutes at a temperature of ca.
22.degree. C. The solution obtained is placed in the Foulard at
20.degree. C. Next, as base material, a 10.times.10 cm polyethylene
terephthalate fleece with a weight per unit area of 40 g/m.sup.2
(longitudinally laid, chemically bonded, air permeability greater
than 1500 dm.sup.3/(m.sup.2s) at 100 Pa air pressure difference,
thickness 0.2 mm) is introduced and drawn through the Foulard
(Sawafill 1122, Sandler Co.). 180 g/m.sup.2 are incorporated into
the fiber structure of the layer.
[0137] The impregnated fleece is squeezed between two rollers and
the polymerization of a mixture, containing acrylic acid, a
cross-linker, a wetting agent and an initiator, is started by UV
treatment. The UV treatment is effected by switching on UV lamps
(Dr Honle Co., type Uvahand 250, 250 W per lamp). The irradiation
time is 10 seconds. The degree of cross-linking of the absorbent
material is about 0.011. The irradiated fleece is washed with water
and dried for four hours at 70.degree. C.
[0138] The weight per unit area of the textile fabric produced in
practical example 1 is 65 g/m.sup.2.
[0139] The swelling rate defines the quantity of water which is
absorbed by the textile fabric within a defined time period, with
this value relating to the dry weight of the textile fabric.
[0140] The swelling rate is determined by measurement of the weight
increase in time periods from 0 to 20 minutes. The weight per unit
area after the swelling is about 1800 g/m.sup.2.
[0141] The thickness of the textile fabric produced in practical
example 1 is 0.3 mm. Its tensile strength is 150 N/5 cm, and its
air permeability is 1800 dm.sup.3/(m.sup.2s) at 100 Pa air pressure
difference.
Reference Example 1
[0142] A further textile fabric was produced according to the
procedure from example 1. However, in contrast thereto, a thermally
bonded polyethylene terephthalate nonwoven with an air permeability
of less than 500 dm.sup.3/(m.sup.2s) is used. As a result, a fabric
according to the invention with an air permeability of 120
dm.sup.3/(m.sup.2s) is obtained.
Practical Example 2
[0143] In order to simulate the blocking of water transport along
cavities in the cable, the longitudinal impermeability produced by
a textile fabric with constant gap height was investigated. The
experiment takes place on the basis of test methods which are
performed on finished underground or undersea cables. In these
experiments, cables are provided with a hole in the side and a
water pressure of 1 m water column applied. After a defined time,
the cable is opened and the run width of the water analyzed.
[0144] The experimental setup used here is described as follows: as
a base plate, a rectangular plate of Plexiglas with two long sides
A (each 350 mm length) and two short sides B and C (each 210 mm
length) is used. On the base plate, a rectangular sample placing
area is marked with two long sides A' (each 297 mm length) and two
short sides B' and C' (each 210 mm length). Here the sample placing
area with its short side B' coincides flush with the side B of the
base plate and the sides A' are positioned equidistant to the sides
A of the base plate and run parallel to these. A DIN A4 sample of
the textile fabric is laid on the sample placing area. The sample
placing area is surrounded by a ground groove of 1 mm depth, which
runs along the sides A' and C'. A flexible silicone hose of 3 mm
diameter is laid in the groove. The hose later serves for sealing
against an applied covering plate. Next to the silicone hose, a rod
of stainless steel of 350 mm length and 2 mm diameter (with round
cross-section) is laid on each outer side A of the base plate.
Next, a covering plate of Plexiglas, which corresponds in its
dimensions (350 mm.times.310 mm) to the base plate, is placed on
top. The covering and base plates are screwed firmly together in
the outer region (outside the sample placing area) each by means of
3 screws/nuts per side A and a further screw/nut pair on the side
B. Thereby the distance between covering plate and base plate, the
gap height, is defined by the previously laid metal rods. The gap
height is ca. 2 mm. Moreover, during the tightening of the screws,
the resilient silicone hose is compressed so that a seal is
achieved in the region of the sample placing area along the sides
A' and C'. On the side B', the sample placing area is opened, which
defines the subsequent run direction of introduced water from side
C' in the direction of B'. Above the sample placing area, the
covering plate has a rectangular opening of size 210 mm.times.50
mm, which with its long side closes with the side C' of the sample
placing area. A box-shaped water reservoir of Plexiglas, which can
be filled with 500 ml of water, is placed on the opening.
[0145] A sealing experiment is performed in two stages. In the
first stage, the water reservoir is filled with 500 ml of deionized
water from an opened separating funnel. The water flows into the
defined gap in the region of the sample placing area. The forward
flow of the water front can be followed very well through the
transparent Plexiglas covering plate. If a textile fabric which is
provided with an absorbent has been inserted, this swells up, the
gap is blocked and the flow front of the water comes to a halt. The
time until the halting of the flow front is measured and designated
as the sealing time. The corresponding sealing path is defined as
the average distance of the water front to the side C' and measured
graphically.
[0146] In the second stage of the experiment, a 1 m high water
column is applied onto the water reservoir via an attached
connector. For this, a separating funnel as water reservoir is
connected with the nozzle by means of a hose and attached such that
the water level in the funnel is located 100 cm above the sample
placing area. The advance of the flow front is then noted as a
function of the measurement duration under constant water
pressure.
[0147] By means of the experimental set-up described, the textile
fabric according to the invention from practical example 1 is
tested. As the comparison, reference example 1 is used as well as a
material in which a super-absorber in powder form (mass of
absorbent: 30 g/m.sup.2) is applied as a coating onto a nonwoven by
means of an adhesive (reference example 2).
[0148] The blocking time and blocking path of the materials are
shown in Table 1. The material known from the prior art, after a
sealing time of 14 s and a corresponding sealing path of 7 cm,
results in a blocking of the flow front. It is found that the
textile fabric according to the invention from practical example 1,
characterized by an air permeability of 1800 dm.sup.3/(m.sup.2s),
leads to a sealing of the cavity in a markedly shorter sealing time
of 9 s and above all with a very much shorter sealing path of 2 cm.
In contrast to this, the textile fabric from reference example 1
with an air permeability of 120 dm.sup.3/(m.sup.2s) exhibits no
sealing against the entry of water. The water introduced flows
completely through the apparatus. An explanation can be found in
that the high air permeability or open porosity of the textile
fabric from practical example 1 enables a very rapid uptake of the
water. Associated with this are a rapid swell rate and low sealing
time.
TABLE-US-00001 Absorbent mass Sealing time Sealing path Example
[g/m.sup.2] [s] [cm] Practical example 1 30 9 .+-. 2 7 .+-. 1
Reference example 30 no sealing no sealing 1 Reference example 30
14 .+-. 2 12 .+-. 1 2
[0149] The analysis of the sealing behavior under constant pressure
of a water column of 1 m height is shown in Table 2.
TABLE-US-00002 Flow front migration; pressure: Absorbent mass 1 m
water column Example [g/m.sup.2] [cm/day] Practical example 1 30
0.5 Reference example 30 no sealing 1 Reference example 30 4.5
2
[0150] In reference example 2, the flow front under constant water
pressure of a 1 m water column migrates at 4.5 cm per day (24 hrs).
On contact with water, the water-soluble adhesive dissolves and the
super-absorber powder swells. Since the adhesive has lost its
function, the swelled super-absorber has also lost its anchoring on
the nonwoven substrate. Under constant water pressure, the swelled
super-absorber is mobile and physically migrates along the cavity.
In contrast to this, the textile fabric according to the invention
(practical example 1) exhibits markedly better long-term sealing
under constant water pressure. The flow front migrates only 0.5 cm
per day (24 hrs). The reason for this is the very much better
anchoring of the absorbent in the base material. Owing to the high
air permeability of 1800 dm.sup.3/(m.sup.2s), for the textile
fabric according to the invention there is a very large contact
surface between the absorbent and the nonwoven substrate. The
absorbent thus surrounds the fibers of the textile layer partly
with bonding, which leads to excellent anchoring and very good
sealing performance.
Practical Example 3
[0151] In order to investigate the effect of various types of
drying, i.e. contact drying and contactless drying, the fabric
produced in practical example 1 was dried once with hot air and
once with a heated cylinder dryer. It was found that with the use
of the cylinder dryer marked sealing of the surface of the fabric
occurred, which was reflected in a significant decrease in the air
permeability. The results are shown in the following table.
TABLE-US-00003 Air permeability Example [dm.sup.3/(m.sup.2s)]
Practical example 1, contact drying 260 Practical example 1,
contactless drying 1800
[0152] While the invention has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description are to be considered illustrative or exemplary and
not restrictive. It will be understood that changes and
modifications may be made by those of ordinary skill within the
scope of the following claims. In particular, the present invention
covers further embodiments with any combination of features from
different embodiments described above and below. Additionally,
statements made herein characterizing the invention refer to an
embodiment of the invention and not necessarily all
embodiments.
[0153] The terms used in the claims should be construed to have the
broadest reasonable interpretation consistent with the foregoing
description. For example, the use of the article "a" or "the" in
introducing an element should not be interpreted as being exclusive
of a plurality of elements. Likewise, the recitation of "or" should
be interpreted as being inclusive, such that the recitation of "A
or B" is not exclusive of "A and B," unless it is clear from the
context or the foregoing description that only one of A and B is
intended. Further, the recitation of "at least one of A, B, and C"
should be interpreted as one or more of a group of elements
consisting of A, B, and C, and should not be interpreted as
requiring at least one of each of the listed elements A, B, and C,
regardless of whether A, B, and C are related as categories or
otherwise. Moreover, the recitation of "A, B, and/or C" or "at
least one of A, B, or C" should be interpreted as including any
singular entity from the listed elements, e.g., A, any subset from
the listed elements, e.g., A and B, or the entire list of elements
A, B, and C.
* * * * *